SwiftUI View to UIView

HostingView Example.swift

import UIKit
import SwiftUI

// SwiftUI
struct SomeView: View {
  
    var body: some View { 
        Text("Hello World!") 
    }
}

// UIKit
class RootViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // SwiftUI View -> UIView
        let swiftUIView = SomeView()
        let uiView = HostingView(rootView: swiftUIView)
    }
}

HostingView.swift

import UIKit
import SwiftUI

class HostingView<T: View>: UIView {

    private(set) var hostingController: UIHostingController<T>

    var rootView: T {
        get { hostingController.rootView }
        set { hostingController.rootView = newValue }
    }

    init(rootView: T, frame: CGRect = .zero) {
        hostingController = UIHostingController(rootView: rootView)

        super.init(frame: frame)

        backgroundColor = .clear
        hostingController.view.backgroundColor = backgroundColor
        hostingController.view.frame = self.bounds
        hostingController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]

        addSubview(hostingController.view)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}